I was installing QT 4.6.2 to Ubuntu I got the below error - Qt configure error: Basic XLib functionality test failed Here is what I did to get rid of the issue. 1. Install libpcap files with "]$ sudo apt-get install libpcap0.8-dev" this library was missing 2. Then install few more libraries which were missing as this was a new ubuntu installation I was working on. ]$ sudo apt-get install libx11-dev libfreetype6-dev libavahi-gobject-dev libSM-dev libXrender-dev libfontconfig-dev libXext-dev ]$ ./configure ]$ make ]$ sudo make install After this set the PATH ]$ PATH=/usr/local/<PATH_TO_QT>/qt4/bin:$PATH ]$ export PATH Thats it !! . Enjoy QT Development. Posted via email from What I See